Touch screen displays are widely used in many different types of products. A few examples of electronic products that use touch screen displays are tablet computers, smart phones, laptop computers, automatic teller machines (ATM) and point of sale (POS) terminals. There are multiple technologies that can be used to implement the touch screen component of a touch screen display. Each of the technologies has advantages and disadvantages. Some of the technologies reduce the amount of light transmitted by the display while other methods have good light transmission characteristics, but are susceptible to radio frequency noise which causes identification of a touch when no actual touch occurred.
Most countries require that electronic products sold in their country meet certain minimum safety and security requirements. The requirements are typically codified in statutes, regulations, standards or documents that specify the tests and measurements that electronic products must comply with for a given country. Products that fail to meet the requirements for a country cannot be sold in that country. The requirements are typically maintained by a government agency, an organization or a company. Some examples of entities that maintain requirements are Underwriters Laboratories (UL), the Federal Communications Commission (FCC) and the International Electrotechnical Commission (IEC).
Some product requirements, such as the electromagnetic compatibility (EMC) requirements from the IEC, specify different levels of compliance for the same apparatus based on how the apparatus is used or the function performed by the system that uses the apparatus. For example, a touch screen display used on a tablet computer is generally held to a lower standard of EMC compliance than the same touch screen display used on a point of sale terminal or an automatic teller machine (ATM). Touch screen displays used on a point of sale terminal or an ATM are held to a higher level of EMC compliance because these systems perform financial transactions and any failure is considered to be critical. If these products are to meet the higher EMC standard, certain technologies cannot be used. For example, certain touch technologies experience failures in the presence of radio frequency noise which cause the apparatus to fail the higher EMC standard.